The Localhost class refers to the PacketShaper traffic; traffic to and from the PacketShaper. (Whenever you access and manage the unit, or send FDR or WebPulse requests, you are generating Localhost traffic.)
SameSide is a traffic class that measures traffic not destined for the WAN; LAN to LAN (Inside Host to Inside Host) traffic that is traversing through the PS (e.g. one arm routing).
An exception class, which is marked with an exclamation point in the traffic tree, has been tagged to sort above standard (non-exception) classes in the traffic tree. Traffic that hits classes at the top of tree will be classified first and the appropriate policy will be applied.
The SameSide class has an ignore policy by default. An ignore policy exempts the traffic class from bandwidth allocation and treats the traffic type as "pass-through" traffic.
The Localhost class has a Priority 6 policy so that traffic to and from the PS is given high priority.
These are the default settings so that PacketShaper management traffic and sameside traffic will be quickly classified and treated properly.